1. Field
The present invention relates generally to dormant handoff in a wireless communication network supporting packet data transmissions, and more specifically, to mobile-unassisted dormant handoff.
2. Background
For data transmissions, such as packet data transmissions, data is transmitted via the network using Internet Protocol (IP) addressing, referred to as Mobile IP routing. IP addresses are used to route packets from a source endpoint to a destination by allowing routers to forward packets from incoming network interfaces to outbound interfaces according to routing tables. The routing tables typically maintain the next-hop (outbound interface) information for each destination IP address, according to the number of networks to which that IP address is connected. Thus, the IP address typically carries with it information that specifies the IP node's point of attachment. For a communication network, this involves forming a series of connections to form a path from the source to the destination. Specifically, a Point-to-Point Protocol (PPP) is used to establish the path.
The network is typically divided into multiple packet zones wherein each packet zone services a particular geographical area. As a Mobile Station (MS) or other mobile node moves throughout the network, the MS may move from one packet zone to another. Such movement may require the MS to establish a new path via the current packet zone and tear down a previous path. This process is referred to as handoff.
For a given MS, when packet data is actively communicated via a given path, handoff is accomplished by use of the signaling messages transmitted between the MS and the network for the packet data activity. During dormant periods when the path is not being used for packet data activity, the MS typically assists the handoff by providing signaling information that identifies the current location of the MS. Handoff during a dormant period is referred to as “dormant handoff,” and the provision of information by the MS during dormant handoff is referred to as “mobile-assisted” dormant handoff. In response to the signaling information, the network establishes a new path and tears down the previous path.
Dormant handoff may occur many times before any packet data is ready for communication to or from the MS. In this situation, paths are established and torn down any number of times, wasting network resources. Additionally, the transmission of the signaling message from the MS associated with establishment of each new path uses wireless resources.
There is a need therefore, to provide efficient dormant handoff that reduces the use of network IP resources. There is further a need to provide efficient dormant handoff without mobile assistance that reduces the demands on the network wireless resources.